The portal has been deactivated. Please contact your portal admin.

Question Video: Recalling the Result of a Postive Food Test with Starch Biology

A sample is tested with iodine. What is the color change that will occur if the sample contains starch? [A] Blue-black to brown [B] Pale blue to purple [C] Brown to brick-red [D] Brown to blue-black [E] Brown to cloudy white precipitate

01:26

Video Transcript

A sample is tested with iodine. What is the color change that will occur if the sample contains starch? (A) Blue-black to brown. (B) Pale blue to purple. (C) Brown to brick-red. (D) Brown to blue-black. Or (E) brown to cloudy white precipitate.

As the question suggests, the food test we use to see if a sample of food contains starch is the iodine test. For example, let’s say we want to determine if this food contains starch. We could add a few drops of iodine solution to this sample of food. This can be done in a dish or in a test tube.

In its liquid form, iodine is usually a light orange to brown color. However, when iodine solution comes into contact with starch, it will turn very dark brown, blue-black, or black. This is known as a positive result because it shows the food contains starch. If there is no color change, it is a negative result, meaning there is no starch present in the food.

So the correct answer to this question is (D). The iodine color change that will occur if the sample contains starch is from brown to blue-black.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.